1. Field of the Invention
This invention relates to flashlights. More particularly, this invention relates to flashlight conductor tubes for receiving the batteries of the flashlight and for establishing electrical continuity between the switch and the bulb of the flashlight.
2. Description of the Prior Art
Flashlights typically comprise a tubular outer casing in which is stored one or more dry cell batteries, a light bulb and a switch for on-off operation of the flashlight. More particularly, there are usually two dry cell batteries which are connected in electrical series contact with one another, having one terminal in electrical contact with the base terminal of the light bulb and one terminal in electrical contact with one pole of the switch. The other pole of the switch is connected in electrical contact with the center terminal of the light bulb. In this configuration, actuation of the switch to an "on" position establishes electrical contact between the terminals of the batteries and the respective terminals of the light bulb, thereby causing the light bulb to light.
In small flashlights, commonly referred to as pocket or penlight flashlights, it has been found that the use of a conductor tube within the outer casing of the flashlight, and a corresponding conductor clip (operating as the switch), provides a convenient means for establishing the desired electrical continuity among the batteries, the switch, and the light bulb. Moreover, it is well known that the use of such conductor tubes has substantially reduced the cost of manufacturing such flashlights.
U.S. Pat. No. 1,839,971 issued to Korsen discloses a flashlight in which the conductor tube comprises a cylindrical or tubular non-conductive sleeve with a conductive strip disposed therein in direct electrical contact with one terminal of the battery. During use, the clip, operating as the switch, engages through an aperture in the non-conductive sleeve to make electrical contact with the conductive strip, thereby permitting the flow of electrical energy to the light bulb to light the same.
U.S. Pat. No. 1,219,109 issued to Kaplan teaches the use of a conductor tube having an inner conductive sleeve disposed within an outer non-conductive sleeve. The Kaplan conductor tube operates substantially similar to the Korsen tube by establishing the desired electrical continuity by means of a clip (operating as a switch), which engages through an aperture in the outer non-conductive sleeve to make contact with the inner conductive sleeve.
Finally, U.S. Pat. Nos. 3,806,724 and 3,902,058 issue to Tanner, et al. and Naylor, et al., respectively, teach the use of a conductor tube comprising a non-conductive, inner sleeve disposed concentrically within a conductive, outer sleeve with the non-conductive sleeve functioning to prevent electrical contact between the conductive sleeve and the conductive casing (cathode) of the battery, thereby eliminating the need for purchasing covered batteries. With the outer tubular casing of the flashlight comprising a non-conductive material, such as plastic, the clip (operating as a switch) engages through an aperture in the outer casing to engage the outer conductive sleeve, thereby completing the electrical circuit to energize the light bulb. More particularly, in these conductor tubes, electrical contact is established between the outer conductive sleeve and the base terminal of the light bulb by rolling in the end of the conductor tube into itself such that the end portion of the outer conductive sleeve is disposed on the lumen of the conductor tube. The light bulb is then fitted into this newly formed socket such that the base terminal of the light bulb is in direct electrical contact with the outer conductive sleeve of the conductor tube.
One major disadvantage to the conductor tube disclosed in the Tanner and Naylor patents listed above, is the necessity to roll in the end of the conductor tube into itself to establish electrical continuity with the base terminal of the light bulb and the outer conductive sleeve of the conductor tube. Experience has shown that the necessity of such rolled in end of the conductor tube dictates the material used for the outer conductive sleeve of the conductor tube. More particularly, experience has shown that the outer conductive sleeve must be manufactured from a relatively thin conductive material so that the end may be rolled in without breaking. Typically, such thin material comprises aluminum or copper having a thickness of approximately 0.001 inch. Because of the required thinness of the material constituting the outer conductive sleeve of the conductor tube, it has been found that the point of contact between the outer conductive sleeve and the clip, operating as a switch, tends to oxidize after relatively few operations of actuating the clip (switch) to engage the outer conductive sleeve. After oxidation, poor electrical contact is made between the clip and the outer conductive sleeve, thereby reducing the illumination emitted by the light bulb due to the reduction in the amount of electrical current flowing thereto.
Another major disadvantage to the conductor tube disclosed in the Tanner and Naylor patents listed above, is the great difficulty in manufacturing the same. Specifically, such conductor tubes are typically manufactured by laminating a layer of conductive material, such as aluminum foil, with a corresponding layer of non-conductive material, such as cardboard, and then rolling the same to produce a cylindrical configuration. The next step in the manufacturing process involves rolling in the end of the conductor tube to form the socket previously described. Obviously, this two-step process in manufacturing the conductive tube substantially increases the cost and complexity of producing the same.
Therefore, it is an object of this invention to provide an apparatus and method which overcomes the aforementioned inadequacies of the prior art conductor tubes and provides an improvement which is a significant contribution to the advancement of the art of producing conductor tubes for flashlights.
Another object of this invention is to provide a conductor tube for flashlights in which the outer conductive sleeve thereof is manufactured from a highly conductive material, such as tin-plated, low-carbon steel which is highly conductive and nonoxidizing to permit full electrical current to flow to the light bulb to energize the same.
Another object of this invention is to provide a conductor tube for a flashlight including means for establishing electrical contact between the base terminal of the light bulb and the outer conductive sleeve of the conductor tube without rolling in the end of the conductor tube as taught by the patents discussed above.
Another object of this invention is to provide a conductor tube for a flashlight including means for providing a socket for receiving the light bulb without rolling in the end of the conductor tube as taught by the patents listed above.
Another object of this invention is to provide a conductor tube for a flashlight having a configuration which is easily manufactured and less costly to produce as compared to the prior art conductor tubes discussed above.
Another object of this invention is to provide a method for manufacturing a conductor tube for a flashlight in which the conductor tube is continuously manufactured from a continuous ribbon of laminated materials, one material comprising a highly conductive, non-oxidizing material such as tin-plated, low-carbon steel, and the other material comprising a non-conductive material.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.